Low temperature cure coating compositions based on crosslinkable, solvent borne, solution polymers containing activated ester groups, as illustrated by U.S. patent application Ser. No. 346,329, filed Feb. 5, 1982, now abandoned and U.S. patent application Ser. No. 377,504, filed May 12, 1982, U.S. Pat. No. 4,446,280 are known to us. In a coating composition of this type, coatings must be prepared within minutes of mixing the polymer with the crosslinking agent.
It is known, as exemplified by Chem. Abstracts 93: 205,753q (1980), that a system with good storage stability is formed by the admixture of a ketimine with an epoxy polymer even though the epoxy group thereof is amine-reactive. Systems of this type require one equivalent of water for each ketimine group in order to hydrolyze the ketimine, thereby unmasking the primary amine group thereof for crosslinking the amine-reactive polymer. In use, the water for hydrolysis is provided by the ambient atmosphere after the composition has been coated onto an appropriate surface. Accordingly, a drawback of systems of this type is the requirement of humidity control to prepare reproducible coatings and a slower curing time.
Hence, there has existed a continuing need for a low temperature cure, two component, solvent borne coating composition having, when mixed, an improved balance between pot life and speed of cure. Therefore, the provision of such a coating composition would constitute a significant advance in the art.